1. Field of the Invention
The invention relates to a reservoir for a liquid circuit, and more particularly to a reservoir construction for ensuring correct feeding of the circuit under all circumstances, even when the reservoir is inverted.
2. Summary of the Prior Art
Reservoirs in liquid circuits act to collect the excess liquid in the circuit for recirculation. They communicate with the circuit by way of an inlet conduit which returns the liquid from the remainder of the circuit, and by way of an outlet conduit through which liquid for the circuit is aspirated by pumps. Since reservoirs of this kind are only partly full the outlet conduit draws from the bottom of the reservoir. However, when the reservoir is inverted, as occurs when it is part of a liquid circuit in an aircraft and the aircraft flies upside-down, or more generally when it is subjected to conditions of gravity reversal, the liquid flows to the other side of the reservoir and leaves the outlet conduit dry, so that the supply of liquid to the circuit is temporarily interrupted.
An arrangement for obviating this disadvantage is disclosed in French patent No. 2621662, from which FIG. 1 of the attached drawings is taken. FIG. 1 shows a reservoir 1 which is divided into two chambers by a perforated horizontal partition 2. The inlet conduit 4 opens into the top chamber 5 and the outlet conduit 6 is at the bottom of the lower chamber 7. A valve 8 is installed below the partition 2 and consists of a flexible diaphragm riveted at its centre to the partition 2 by an element 3. The liquid entering from the inlet conduit 4 accumulates on the partition 2, flows through the perforations therein and bends the valve 8 into an umbrella shape to allow it into the lower chamber 7. When the reservoir 1 is inverted, the liquid filling the lower chamber 7 weighs on the valve 8, which thus closes and prevents the liquid from returning to the top chamber 5. The outlet conduit 6 is extended by a tube 9 which projects into the lower chamber 7, and is able to aspirate liquid provided the liquid level in the chamber 7 is above the edge 10 of the tube 9xe2x80x94i.e. provided the liquid occupies substantially the volume 11 indicated in FIG. 1. However, supply of liquid to the circuit is still interrupted when the volume 11 falls, so that in practice the reservoir 1 must be larger than the conventional reservoirs in order to accommodate the tube 9 and the required volume of liquid around it, such volume remaining stagnant and unused under normal flight conditions.
Constructions are also known in which the reservoir comprises a partition which divides the reservoir to define a bottom chamber therein and which is provided with at least one aperture. The liquid inlet and outlet conduits both open into the bottom chamber and the partition aperture is arranged to remain permanently open whatever the position or orientation of the reservoirxe2x80x94i.e., the partition is valveless. Since the bottom of the reservoir is fairly close to the partition, the reservoir volume is reduced. The bottom chamber is normally completely full and the excess liquid forms a reserve in the top chamber. When the reservoir is inverted the inlet conduit continues to feed liquid into the bottom chamber so that the outlet conduit cannot run dry even during a long period of inversion. Liquid leakage from the bottom chamber is tolerated but total emptying of the bottom chamber is avoided if the partition is constructed as an inverted tray or if the apertures in the partition are bounded by edges extending from the partition towards the bottom of the reservoir.
However, this construction cannot ensure that liquid leaving the reservoir through the outlet conduit is completely free from gas bubbles, because bubbles introduced into the reservoir through the inlet conduit accumulate below the partition under normal conditions and rise through the bottom chamber towards the outlet conduit when the reservoir is inverted. Also, hydraulic control circuits for engines, a field in which the invention is particularly applicable, are usually well degassed except in special circumstances such as purging or abrupt manoeuvring, when large gas bubbles may be formed and may therefore occupy much of the bottom chamber and be aspirated through the outlet line even if positive gravity is maintained. The apertures with which the partition is sometimes provided for gradually removing the gas from the bottom chamber are then ineffective, and they still have the disadvantage of allowing the bottom chamber to empty during a prolonged period of negative gravity. Because of this, the construction in unacceptable and the present invention aims to overcome these disadvantages.
Accordingly, the invention provides a reservoir for a liquid circuit, comprising a partition dividing said reservoir to define a bottom chamber therein, means defining at least one aperture in said partition adapted to remain open in any position of said reservoir, a liquid inlet conduit opening into said bottom chamber, a liquid outlet conduit leading from said bottom chamber, a deaerator mounted on said partition in communication with said bottom chamber, said deaerator having a degassing orifice which opens outside said bottom chamber, and a valve which is operable by gravity to close said degassing orifice when said reservoir is inverted or subjected to negative gravity.
The deaerator extends through the partition with its degassing orifice disposed outside the bottom chamber, with the result that the contents of the bottom chamber remain completely liquid and the feed to the circuit is of good quality. Also, leakage of liquid through the degassing orifice in the event of inversion is prevented by the valve which is associated with the orifice and which closes under gravity in the event of inversion or negative gravity.